In a news conference, officials said the suspect was 38-year-old Christopher Boone Lacy of Corning. He was also shot in the head and died.

On Wednesday, the officer's family and dozens of officers kept vigil at John Muir Medical Center in Walnut Creek.

The shooting prompted the closure of the Interstate 680 in both directions as traffic came to a standstill.

The incident occurred shortly before 8:30 a.m. Tuesday after the officer conducted a traffic stop, CHP and Contra Costa County sheriff's officials said.

Youngstrom was reporting to a call of a dead deer, and was nearby when his beat partner made a traffic stop. Youngstrom assisted in the call.

Lacy, the sole occupant of the vehicle, had a short talk with Youngstrom before the officer walked away.

It was then that Lacy pulled a gun and opened fire at the officer after they spoke, Sheriff's spokesman Jimmy Lee said during a Wednesday news conference said.

Sgt. Diana McDermott, a CHP spokeswoman, said she knows Youngstrom personally, and thanked the public for its support as his family gathered at the hospital.

"As you can imagine, this is a very difficult situation for us," McDermott said. "We appreciate all the calls and concerns from the public. We thank you very much. It means a lot to us."

California Highway Patrol officers somberly went in and out of the hospital throughout the day, consoling each other and occasionally conferring with hospital security and medical staff.

"We are like a family, but it's not just us, it's everybody. The community, the media, the public -- we're all a family and this affects all of us," McDermott said. "Being strong for each other is very important. (Youngstrom's) family will be in all our prayers and thoughts."

Witness Gene Russell told KRON-TV that he heard loud popping sounds while traveling in his car on southbound I-680. He looked under the vehicle next to him and saw an officer down.

Russell said he then saw a second officer shooting at the vehicle.

"I would say he emptied his gun," Russell said. "The traffic continued to roll. My response was, 'I'm in a soft-top car. I need to get as far away from there as possible.'"

Youngstrom was described as a loving husband and father of four.

The community of Fairfield is planning on holding a candlelight vigil at 7:30 p.m. on Wednesday.